Reproductive Anatomy
The male genitals: The genitals include those organs or parts of the body that are involved in the process of reproduction. There are external and internal genitalia.
The male external genitals include the penis and the scrotum. The male internal genitalia include the testes, epididymis, the ductus (or vas) deferens, the prostate, the seminal vesicles, and the urethra.
The female genitals: The female external genitalia include the vulva, which is comprised by the labia and clitoris. The female internal genitalia include the vagina, cervix, uterus, fallopian tubes, and ovaries.
The male and female gonads are the sex organs that produce the gametes, or the reproductive germ cells. The female gonad is the ovary, while the male gonad is the testis. The ovaries produce the female gametes, the ova, while the testes produce the male gametes, the spermatozoa.
Gametogenesis
Spermatogenesis: Spermatogenesis takes place in the seminiferous tubules of the testes. The seminiferous tubules contain undifferentiated diploid cells called spermatogonia. The spermatogonia divide and enlarge and undergo genomic replication to produce primary spermatocytes. The spermatids mature within the epididymis to produce a flagellum and the acrosome, which houses derivative enzymes important for fertilization.
Oogenesis: In oogenesis, a haploid ovum is produced from a single diploid oogonium in the ovaries. A diploid oogonium begins meiosis to produce a primary oocyte. The primary oocyte undergoes meiosis I with unequal division of the cytoplasm to produce a large secondary oocyte and a small polar body.
Sexual Reproduction
Ovulation involves the release of a mature ovum from one of the two ovaries in response to hormonal signals. In the ovaries, each mature ovum is enveloped in a layer of supporting cells. This structure is known as a follicle. When sperm encounter the ovum, enzymes within the acrosome allow it to degrade and penetrate the corona radiata and zona pellucida. A placenta forms from embryonic and maternal tissues to allow the transfer of nutrients to and waste products from the fetus.
