This is a print version of story In-vitro w/s****r-in-law part 1 by CoolJ66 from

In-vitro w/s****r-in-law part 1

I've been happily married for several years to my wife Tracy and have a great sex life. My wife's younger s****r Sara has always been someone who I've lusted after.
While her breasts are slightly larger than my wife's, her ass cheeks while nicely shaped, they are longer. This means over the years when we swim together at f****y outings more cheek comes out of the suit.

Being an ass freak this made me consistently log images of her ass to the masturbation Rolodex in my mind! Never in my wildest dreams did I ever expect what would take place over the next few weeks.
Sara has always been a career lady and did not marry until her mid 30s.
After several years of trying to conceive with her husband Bill there were still no c***dren. Bill had some k**s from a previous marriage and this caused more pressure on Sara to have a baby of her own. I had overheard my wife on the phone with her on occasion discussing how bad things were getting, she seemed to be trying all types of fertility d**gs with no success.

A month ago I come home and my wife says Sara is moving in with us for 6 weeks.
I asked "what's going on? She said "there is a fertility clinic here in town that is one of the top clinics in the country that Sara wants to use as a last resort to save the marriage". Sara who lives four hours west of us needs to stay here and you need to help! What??

Well apparently shots have to be given twice a day to increase egg production, then after ovulation they will be harvested, inseminated with Bill's sperm and put back in Sara to hopefully grow. Since my wife and her side of the f****y is squeamish at the site of bl**d or needles, my wife volunteered that I would take care of this. We moved her into a bedroom on the other side of our house which had it's own bathroom right outside. Before Sara arrived I watched a video from the clinic on how the intramuscular shots were to be given.

On the video it shows the woman leaning over a sink while taking the weight off one foot and the shot being administered in her butt cheek. Since the gauge of the needle is thick it is painful and you should alternate between cheeks.

Sara arrived and we got her moved in. We ate dinner and decided one shot for her stomach would be done in the morning and the bigger needle (butt) shot would be done around ten at night. That night she came to my room and said she was ready. I asked "should we do it here in the bathroom?" (like it showed on the video? Sara said "No, it hurts so bad I have to lie on the bed and squeeze a tennis ball". I found out Bill had given her the first few shots and was not very good at it.

Now I was intrigued, she walked me into her room and locked the door saying she did not want the k**s or our dog barging in while doing the injection. She was wearing a little tank top and some loose comfy shorts and some panties.
Sara got on her stomach on the bed, grabbed a pillow and the tennis ball and tensed up. This meant I would be in control of pulling her pants down. Now my heart is racing and my cock is starting to swell. I'm finally going to be able to gaze upon the ass I never thought I would see. She even nervously giggled and apologized that I would have to see her butt!!!

Well I said "don't worry about it, I only want to help and I would love more k**s in the f****y". She asked why I had brought a bowl of warm water and a washcloth? I told her after a shot deep in the muscle the injection site should be massaged with a warm compress. Now I set everything in place next her on the bed, sat down and gently pulled her shorts and panties down well below her cheeks. I sensed her apprehension and stated I did not want the elastic to snap up over the cheek and possibly break the needle off in her.

She relaxed and I looked down at the most beautiful butt cheeks I had seen up close in twenty years since I've been married. My cock was 8 inches of steel pushing down the leg of my warm ups. I wiped her cheek with alcohol, gave her the injection and immediately started massaging her with the warm washcloth.

I started in a circle and gradually started rubbing in wider circles. This pulled her cheeks open and I started to see the brown skin around her anus and even her taint and the back of her vagina!!!.......My cock was leaking badly. I finally had to stop, pulled up her pants and lucky for me she said I had done it with much less pain than Bill had and lucky for me she wanted me to stay and talk about her marriage for a few minutes, this allowed my cock to soften enough so it would not be obvious when I stood up. Sara thanked me and I went to my room where Tracy was watching TV. I told her I was horny and asked if she would put on the terry cloth shorts from high school that were way too small(she is 41 now)and f***e a lot of ass cheek out of the bottom. Tracy squeezed into them and gave me a show.

I asked her to get on her hands and knees at the edge of the bed and I slowly pulled the shorts half way down her thighs thinking of her s****r's ass the whole time. I bent down and licked her pussy a few times and then her butthole for a few minutes. My cock slid into her pussy to the hilt easily and I gently started to plow in and out, looking down and watching her asshole clench up as she squeezed my cock...this lasted for 3-4 minutes before I blew a massive load deep in her s****r's hole...wait my wife's be continued....

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