After pausing for a brief moment to check the address of the building, Al stepped through the automatic doors and into the waiting area. For all intents and purposes it looked like a doctor's office, complete with uncomfortable chairs, magazine racks, a TV in one corner of the room, and even a large potted plant encroaching on the seat next to it. But if Al's sister Mystic was to be believed, this was actually a medical research laboratory, one that was very interested in studying extraterrestrial creatures like him. And his sisters, apparently, but they'd told him they'd already visited; the lab wanted to study a male Starry-Eyed next, and that he would be paid well for his time.

And so, he'd put on his best clothes: a gray suit jacket and pants with a white button-up shirt, mostly covering his orange skin. He still got some curious looks from the other visitors in the waiting room, naturally, as aliens weren't exactly common, especially those like him with bright orange eyes filled with white dots rather than pupils. Even his hair was vibrantly apricot-colored, as was the tuft on the end of his lion-like tail. He was quite used to it though, and after informing the receptionist that he was there for an appointment, he took a seat, reaching for the magazine rack out of curiosity to see if–

His hand was still an inch from a promising culinary magazine when the double-doors at the back of the room were flung open by a dark gray wolfess in a labcoat, who held the doors open with both arms in a dramatic pose. Her eyes immediately fell on him, as his bright orange exterior made him stand out from the crowd, and she called out, "Al! Please, come with me."

A little bemused, he straightened up and turned to face her fully. "I'm a little early," he began, only for her to cut him off.

"And I'm ready now, so come along," she urged.

Al headed over to the doors and followed her down a pristine corridor past various examination rooms, offices, and storage rooms, according to the signs he read idly on the way. She brought him to an intersection of four rooms with frosted glass windows, one of which seemed to have some additional layer of something on the glass to prevent seeing inside of it. Narrowing his eyes, Al could have sworn that it was some sort of white liquid flowing down the inner side of the glass, but what could it–?

"Ah, good, Beta-One is all set up like I asked," the wolf doctor said, bringing Al's attention over to her. She swiped a keycard through the reader at the door to unlock it and led him inside. It seemed like a perfectly ordinary examination room to Al, though quite a spacious one, with a long counter along one side of the room, including a sink and many cupboards. The long mirror on one side of the wall was an interesting feature, and the doctor waved him over to an examination table, patting it to indicate for him to take a seat.

"Thank you for volunteering, I've been looking forward to the opportunity to study more of the Starry-Eyed," she mused as she returned to the cabinets, pulling out more things and setting them on the counter.

Al took his seat on the examination table. "Oh? You're the one who studied my sister?"

"Mystic was your sister? Yes, yes, she was very cooperative, I got some excellent results out of my session with her." Straightening up, she turned back to him, catching him off-guard when he saw that she had unbuttoned her labcoat, and that she had nothing on underneath but a stethoscope. Her large breasts hung freely, pink nipples standing out from the gray fur around them, but the generously large cock draped over the front of an equally potent fur-covered ballsack was the greater surprise. "Ah, but I'm getting ahead of myself. I'm Dr. Fang: principal clinical trial manager, sexual researcher, and as of late, xenobiologist."

"That is quite the repertoire," Al remarked. Curious, he pointed to her loins with one finger and inquired, "If you don't mind my asking, are you...?"

Chuckling, she answered him by turning around and lifting her tail high, letting the rear tails of her labcoat fall to either side of her hips. Above her heavy-hanging balls, she had both holes on display, the pink flesh of her slit standing out easily amidst her fur. "Fully equipped, yes," she teased, before turning back to face him again. "And a little enhanced by my research, so don't feel too intimidated. Speaking of which, let me see what you've got to work with to start, shall we?"

She came over to him and reached for his belt, expertly undoing the clasp and opening it up. Al could certainly feel how tight his pants were and welcomed the chance to take them off, but as she leaned in close to undo the button and zipper, he tried to warn her, "Uh, doctor..."

"Oh, I know what I'm doing," she reassured him, hooking her fingers under the waistband of both his pants and underwear. "Don't worry, I've handled much bigger–"

That was as far as she got; when she pulled downwards, his cock sprung free, smacking her on the underside of her muzzle. More stunned than anything else, she staggered back one step, then shook her head and turned her attention back to him, her eyes widening: there'd been no sign of it to her, but the throbbing orange shaft jutting from between his legs had to be well over two feet long, even bigger than she was. The balls hanging between his legs, meanwhile, were equally impressive, each nearing the size of watermelons.

"My, my, you hid that well!" Dr. Fang complimented, reaching for a drawer under the counter, retrieving a tape measure.

"Yes, my clothes are specially tailored to conceal it," Al explained, watching her as she started taking measurements, the wolfess silently nodding in approval with each one, finishing with his cock by pressing a digit against his tip. Her fingertip slipped inside with surprising ease, making him groan aloud, and she hummed to herself before withdrawing her finger and moving on.

"I'd love to examine them later, though I'm more well-versed in alien biology than alien technology," she murmured, taking her time wrapping the tape measure around his sack in various ways. "I'm far more interested in you. Some results from my previous experiments have shown your bodies have some very fascinating adaptations I would like to test out." Grabbing a small handheld scale, she raised it up underneath his loins to let his heavy testes rest atop it so that she could weigh them.

As she stepped aside to write down the measurements she had taken, Al calmly stripped his lower clothing off his legs entirely and piled it up on the examination table next to him. "What adaptations?"

"Elasticity!" Dr. Fang announced as she turned back to him. "I gathered some very interesting preliminary results when my nephew- ahem, my assistant and I examined your sister..." She stared off absently for a moment as though reminiscing, and Al couldn't help but notice that her recollection of whatever happened made her partly-aroused shaft rapidly rise to full hardness. Clearing her throat after a moment, she grabbed a step-stool and dragged it over in front of the examination table. "Anyhow, I had been just planning on a saline feed, but as you are far more endowed than I anticipated, I have a much more enjoyable method of capacity testing in mind." Taking a moment to grab a bottle of what must have been lubricant off the side counter, she instructed "Spread your legs for me, would you?" as she poured the clear fluid onto her erection liberally.

Curious to see what she had in mind, Al obliged, and she stepped up onto the step-stool, her right hand holding her cock while her left reached out to grab his. Though his endowment was impressive, hers was too, and as she eased her cockhead inside of his he could see his shaft visibly expanding and stretching around it, distended by the shape of Dr. Fang's girth. His hands gripped the edges of the examination table, and as she slid inch after inch into him, she inquired, "Mmh, have you ever done any experiments like this on your own...?"

"Not quite like this, but yes," he grunted, one eye closed as he watched his cock stretch around hers, feeling his urethra expanding to accommodate her, while she adjusted her grip to hold his cock with both hands. Without thinking, he reflexively asked her, "You?"

She gave a little chuckle interrupted by a gasp as she hilted in him, his stretched cockhead pressed against her crotch. "Many, in the name of my research," she replied with a smirk. Maintaining her grip, she drew her hips back to pull halfway out from him before sinking back in a sharp thrust, moaning out along with him as she repeated the motion, drawing back steadily before shoving her hips forward rapidly. "I suspect we will both learn a great deal...!"

Panting for breath, she continued thrusting the full length of her cock into his own, gripping with her hands to create tighter spots for her to thrust through, giving extra pleasure to both of them. Her balls swung forward after each thrust, bouncing between the underside of his stretched cock and her inner thighs, while his own sack wobbled and swayed slightly from the force of her movements. Her open labcoat also gave Al quite the sight to admire as her breasts bounced freely before his eyes, though he remained in his seat and let her take control, his hands clutching the edge of the exam table tightly.

After a short time she began to alter her pace, as his shaft began accepting hers more easily into it on each thrust. Pounding into him more rapidly for a short burst, she then slowed down while she caught her breath, pulling almost all of her throbbing dick out of his own before sliding the full length of it back inside. Though she was leaking precum into him, it mingled with his as her cock became covered in the resulting mixture of fluids, allowing her to fuck him even harder and faster the next time she picked up the pace.

She continued to alternate between the faster and slower cadences until she felt herself approaching her orgasm. "Brace yourself, it's coming...!" she warned him in a teasing tone, her head tipping back as her eyes closed, reveling in the tingling sensation of her approaching climax. He gave a grunt of acknowledgement, taking heavy breaths of his own, and several thrusts later Dr. Fang hit her peak. Hilting inside of Al's cock and shuddering from head to toe, her tail wagging in a blur, she began to unload one enormous burst of cum after another, each shot so great it made the bottom of his cock bulge outward on each surge of her seed.

Al shuddered and rocked in place on the table as he felt her filling him up; her hot cum poured into him in huge bursts, flooding into his balls. Her bowling ball-sized nuts were just as potent as they looked as she continued to pump more and more cream into him, with not a drop escaping around her shaft as she clutched his dick tightly with both hands. And with every rope of cum that erupted from her tip, his sack wobbled and expanded to hold it, hanging heavier and lower the more she emptied her own balls into his.

When she finally came down from her climax and was left panting, his orbs had grown larger than basketballs. She pulled out from him and stepped down from the step-stool, making Al gasp as her shaft slid out of his own, and even as she breathed deeply in recovery she leaned over and put her stethoscope on, pressing the end of it to each of his nuts in turn, listening to them churn. He could only pant for breath as she continued her work even as her softening cock occasionally dripped onto the linoleum floor, the doctor taking more measurements, weighing his nuts again, and giving an experimental tug on the skin of the sack itself.

"Impressive..." she murmured, reaching into an inner pocket as she stood up. "Your capacity certainly exceeds my expectations by far. While I could continue this method of testing expansion, I only have so much time available today, so in the interests of expediency..."

She pulled a remote control out of her labcoat and pushed a button on it, causing a panel in the ceiling to slide aside. Two long tubes descended, one with a big open plastic cap on the end shaped like half of a cylinder with rounded edges, while the other had a conical stainless steel cap fitted with a valve, resembling the end of a hosepipe. As soon as they were low enough Dr. Fang snatched the hose with one hand and tugged it closer, giving it a yank every so often to pull down more of it.

"What's this?" he asked.

"A saline supply – quite a bit more than a 'drip', I assure you," she told him. Taking his cock in her left hand, she pushed the end of the hose into his urethra, stretching it out again. "All I want you to do is tell me when you think you're full – or if you feel an orgasm approaching. We'll see just how much you can really hold."

"All right," he agreed, unsure of exactly what kind of scientific research this was – but she was the expert, after all. She held the hose steady with one hand as she turned the valve, and a flow of fluid picked up and sprayed into his shaft. He gave a groan not just from the sensation but also from the saline solution being at room temperature, in sharp contrast to the heat of Dr. Fang's cum that was still roiling with his own inside of his sack. Unlike during her orgasm, the flow was steady and constant, and she held both his shaft and the hose to ensure they remained connected.

His sack wobbled as the orbs within were filled, expanding readily as she watched. Taking her hand off his cock after a few moments to open the valve even further, cranking it up to full, she listened to him panting as she flooded his sack with saline solution, bloating his balls out to the size of beach balls in short order. Even when they touched the floor, she let the flow continue, dividing her attention between his nuts and his face – though his only reaction was to pant for breath in between his moans of pleasure.

It was a truly unique feeling, and he lost focus on everything beyond the sensation of the saline fluid being pumped through his cock and down into his balls. Coming into contact with the cold floor momentarily took him by surprise, and as his sack continued to grow to accommodate the fluid filling it up, it spread out across the floor, wobbling and sloshing louder the bigger it got. Dr. Fang had to step back at first as his scrotum pushed against her legs, keeping her arms extended to hold the hose in place. The arrangement soon became impractical when his sack came to resemble an overstuffed beanbag chair, and she simply climbed on top of it, her weight barely noticeable against the incredible pressure inside.

"Still feeling fine?" she inquired calmly even as she had to shift to maintain her balance on his wobbling, expanding balls.

"Y-yes, I'll let you know!" he promised, eyes shut tight, gritting his teeth in pleasure. He could feel his orbs churning around the incoming fluid, but there was just so much of it; his cum and hers both paled in comparison to the sheer amount of saline solution pumping into him. Bigger and bigger both nuts grew, spreading across the floor, so large that his own legs were resting on them. Before long Dr. Fang sprawled out atop them, lying down on the rising surface of his orange sack, hands clutching his cock and the spewing hose to keep them together while taking the opportunity to visually inspect his balls up close.

Al started to get a little worried when he felt his balls press against the far side of the room; even with the larger than normal examination room, his capacity was too great to be contained within the four walls. And his orbs were raising Dr. Fang upwards too, the dangling head of the other tube getting pushed aside by his expanding nutsack, the churning of those two testes getting loud enough to drown out the hum of the fluorescent lights overhead. The rate at which his balls swelled slowed the larger they got, but the hose was still spraying at full blast into him, and the constant flow of fluid was stimulating the entire inside of his enormous orbs...

Dr. Fang was halfway to the ceiling when he felt a tingling running through him, and he gasped out, "G-gonna cum!" with his voice raised enough to be heard over the noise of his roiling orbs. She responded just as quickly, releasing the hose, letting it spray saline solution onto his titanic ballsack as she twisted her body to grab the other hose, sliding the cup at the end around his copiously leaking cock instead, pressing the rubber padding at the end to his crotch to form a seal. One finger pushed a button on the hose, and it suddenly began to suck powerfully, stimulating his throbbing and drooling shaft enough to push him the rest of the way over the edge.

He tried to buck his hips as he moaned, but the sheer weight of his balls prevented him from moving far. His entire sack clenched, sending Dr. Fang sprawling, and his shaft swelled out around the enormous eruption that shot into the collection tube, sucked off up through the ceiling. It was pretty much entirely saline, and the less viscous fluid fired into the collector in far larger eruptions than normal as a result. Every clench of his sack sent it rolling back and forth underneath the doctor, and though it shrank in size as the contents were blasted through the sucking collection tube, there was a lot inside of those balls to pump out.

As Al's orgasm went on, Dr. Fang managed to grab the hose and turn it off, though she ended up slipping right off of his wet sack shortly thereafter. And every progressive potent blast he unleashed became thicker and whiter, less saline and more cum that his orbs had churned up. Dr. Fang stood back up to watch the final moments – though it was more like 'minutes' – of his climax, observing his sack returning almost to its normal size. Even once he was fully drained and flopped onto his side on the exam table, his balls still were bigger than they had been before the experiment.

Turning off the suction, she gave him a moment to recover as she retrieved her clipboard, ignoring the erection standing from between her legs to dutifully make notes. "I look forward to seeing just how much is in the collection tank later," she remarked idly as she wrote.

"Well..." he replied, taking a few heavy breaths after getting her attention. "That wasn't... my limit... I could... have held... much more."

She arched an eyebrow. "Is that so?" she replied with a smirk, turning over the page on her clipboard to start writing ideas on the back. "Then I'll have to arrange a true test of your limits soon. How does next Thursday sound?"
 