CHAPTER 27 Reproduction and Embryonic Development Modules 27.2 – 27.3

27.2 Reproductive anatomy of the human female HUMAN REPRODUCTION 27.2 Reproductive anatomy of the human female Ovaries Contain follicles that nurture eggs Produce sex hormones Oviducts Convey eggs to the uterus Ovaries Oviduct Corpus luteum Follicles Uterus Wall of uterus Endometrium (lining of uterus) Cervix (“neck” of uterus) Vagina Figure 27.2A

Uterus Vagina Development of fertilized egg Opens into the vagina Receives penis during intercourse Forms the birth canal Ovaries Oviduct Corpus luteum Follicles Uterus Wall of uterus Endometrium (lining of uterus) Cervix (“neck” of uterus) Vagina Figure 27.2A

Ovulation An egg cell is released from a follicle at the surface of an ovary The orange mass below the ejected oocyte is part of the ovary Egg cell Figure 27.2B

Bladder (excretory system) Rectum (digestive system) Oviduct Ovary Uterus Bladder (excretory system) Rectum (digestive system) Pubic bone Cervix Urethra (excretory system) Shaft Vagina Glans Clitoris Bartholin’s gland Prepuce Labia minora Labia majora Vaginal opening Figure 27.2C

27.3 Reproductive anatomy of the human male Semen Sperm, which are expelled through the ducts during ejaculation Glandular secretions that carry, nourish, and protect the sperm Testes Produce sperm Located outside abdominal cavity within the scrotum

Bladder (excretory system) Seminal vesicle (behind bladder) Prostate gland Bulbourethral gland Urethra Erectile tissue of penis Scrotum Vas deferens Epididymis Testis Glans of penis Figure 27.3B

Bladder (excretory system) Seminal vesicle Rectum (digestive system) Pubic bone Vas deferens Erectile tissue of penis Ejaculatory duct Prostate gland Urethra Vas deferens Bulbourethral gland Glans of penis Epididymis Testis Scrotum Prepuce Figure 27.3A

There are two stages of ejaculation First stage of ejaculation Sphincter contracts Bladder Urethra region here expands and fills with semen Contractions of vas deferens Contractions of seminal vesicle Contractions of prostate gland Contractions of epididymis Sphincter contracts Figure 27.3C

Second stage of ejaculation (expulsion stage) Sphincter remains contracted Semen expelled Contractions of muscles around base of penis Contractions of epididymis Sphincter relaxes Figure 27.3C

Androgens stimulate sperm production They also maintain homeostasis by a negative feedback mechanism that inhibits the secretion of FSH (follicle-stimulating hormone) and LH (luteinizing hormone)

Negative feedback Androgen production Testis Sperm production Stimuli from other areas in the brain Hypothalamus Releasing hormone Anterior pituitary Negative feedback FSH LH Androgen production Testis Sperm production Figure 27.3D