If you’re a man reading this, congratulations, because you produced billions of sperm cells throughout the course of last week; but if you happen to be a woman, hard miss, you need a lot of time before you ovulate — even lay just a single egg. How on earth in the sweet name of nature do men produce more sperms as compared to women who produce few ova in their lifetime. Understanding the anatomy of both sexes is really crucial. Okay, ladies and gentlemen, let’s learn some biology.
Related media: Reproductive System, Part 1 – Female Reproductive System: Crash Course A&P #40
Female Sex Anatomy
The female reproductive system is pretty complicated, why not, because ladies are very delicate and need quite some time to get things working. There are two developments cycles of the female reproductive system: the ovarian cycle and the menstrual cycle.
The ovarian cycle is responsible for creating eggs in the ovaries. It starts in the ovarian follicles in the ovaries, these are tiny primary oocytes — a sort of incomplete proto-eggs. Females are born with all these primordial follicles, about a million oocytes. The actual process of egg creation known as oogenesis are delayed until puberty.
Cherry O Cherry O Babe!
Everyday — even right at birth — a bunch of follicles will begin the process of maturation into oocytes, gradually changing from primordial follicle into late tertiary follicle. This process takes a long ass time, about 375 days or so, to complete. Starting around puberty, sex hormones from the hypothalamus and the pituitary glands set up two concurring cycles: the ovarian cycle in the ovaries, and the menstrual cycle. The hypothalamus secretes Gonadotropin-releasing Hormones (GnRH) about once a month.
This is the hormone that stimulates the pituitary glands to release two more hormones: Follicles-stimulating Hormones (FSH) and Luteinizing Hormone (LH). The FSH lives up to it’s name by stimulating the growth of a follicle cell in the ovaries, but unfortunately, only one follicle cell, the one furthest along the line in for development at the time. The FSH drives that one lucky follicle to keep itself growing by triggering the release of its own hormones, (you guessed it), estrogens. This makes the follicle to mature even more.
The estrogen hormones stimulate the pituitary glands once again to secrete the LH to finish the job of oogenesis. The LH finally triggers the follicle to start diving again and getting it to complete meiosis one and move on to phase two. This whole process takes 14 days, at the end of which it is now mature, pushes itself against the ovary wall, raptures, and with the help of enzymes, breaches the wall and ejects one single mature oocyte.
Congratulations ladies, you’ve now ovulated. (But that’s too long of a time as compared to men).
Related media: Reproductive System, Part 2 – Male Reproductive System: Crash Course A&P #41
Male Sex Anatomy
On the other sex, the male reproductive system is also quite complicated, as well. The structures of the male reproductive system include the testes, the epididymides, the penis, and the ducts and glands that produce and carry semen.
Here’s a question for you guys: Why are the most important parts of the male reproductive system literally hanging out?
The testes are tasked with making male gametes, sperms, and the androgen hormone, testosterone. But unlike the ovaries which are protected and kept in the body, the testicles dangle outside. This is because the testes have to be outside the body cavity to reach the lower temperature necessary for spermatogenesis or sperm production.
Oh Boy! ‘Juice’ Up My Day
Each testes is made up of roughly 250 sections called lobules, which contains seminiferous tubules. These tubules are the sperm factories, made of a central fluid-filled lumen. This sperm-making process is supported by cells throughout and around the tubules: the sertoli cells, which nourishes sperm development (just like the female follicle cells helps the oocytes); and the leydig cells, which releases its own hormones (you guessed it), testosterones.
(Compared to oogenesis, spermatogenesis is a pretty cheap and easy process, biologically speaking).
At puberty, the hypothalamus starts secretes GnRH, which signals the pituitary glands to release the FSH and LH. The FSH stimulates the sertoli cells by secreting Androgen-binding Protein (ABP), and the LH spurs the leydig cells to secrete even more testosterone. This creates large local concentrations of the formula, which is ultimately what triggers sperm production. The target of the testosterones are the outermost cell in the tubules, known as spermatogonia — a sort of incomplete proto-sperm — which set the sperm-making process in motion, by dividing.
A spermatogonia cell uses mitosis to continually divide into two identical daughter cells. The testosterones causes them to divide differently: instead of splitting them into two identical spermatogonia cells, they begin producing two distinct cels. The ‘A’ cells stay up and keep on dividing, so you never run out; but the ‘B’ cells get pushed down the tubule toward the lumen, and turn into primary spermatocytes. They go through meiosis I, and form two more smaller haploid cells called secondary spermatocytes, then rush through meiosis II, and form a total of four round spermatids.
These spermatids now have all of the 23 chromosomes they need for fertilization. They go through the final process of elongating to grow a tail (you know where this is going, huh?) and then become a true mobile sperm known as spermiogenesis. This whole process took about five weeks; but in the end, if each primary spermatocyte gives rise to four actual sperms, and considering how many spermatogonia are dividing up, then a male could produce 1,500 sperms per second. Doing the math, you’d now understand why we made up this fact.
Congratulations gentlemen, you’re billionaires, spermatogenetically speaking.
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Written by: Nana Kwadwo, Mon, Dec 17, 2018.
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