Unit #5 - Reproduction and Genetics

• Scrotum: sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at the root of the penis.
• Extra chromosomes exist in the genome due to errors during meiosis.
• The external positioning of the scrotum keeps the testes 3 degrees lower than core body temperature, which is needed for sperm production and to avoid cancerous growth.
• Testes consist of a seminiferous tubule, lobule, rete testis, epididymis, and ductus deferens.
• The ampulla of the ductus deferens stores sperm.
• Seminal vesicles make semen.
• Prostate gland activates sperm.
• Bulbourethral glands produce mucus to clear the urethra.
• Seminal Vesicle lie on the posterior wall of the bladder and secrete 60% of the volume of semen.
• Semen is a viscous alkaline fluid containing fructose, ascorbic acid, coagulating enzyme, and prostaglandins.
• Sperm and seminal fluid mix in the ejaculatory duct and enter the prostatic urethra during ejaculation.
• Prostate gland is a doughnut-shaped gland that encircles part of the urethra, its milk, a slightly acid fluid, contains citrate, enzymes, and plays a role in the activation of sperm.
• Bulbourethral gland are pea-sized glands inferior to the prostate which produce thick, clear mucus prior to ejaculation that neutralizes acidic urine in the urethra.
• Meiosis reduces the chromosome number by half; introduces genetic variability.
• Meiosis I: copy those chromosomes, leaving you with 92 chromosomes, 4 of each chromosome.
• Meiosis II: divide out those 4 chromosomes into 4 different cells.
• Ovaries are the primary female reproductive organs that make female gametes (ova) and secrete female sex hormones (estrogen and progesterone).
• Accessory ducts include uterine tubes, uterus, and vagina.
• Internal genitalia: ovaries and the internal ducts.
• External genitalia: external sex organs.
• Each follicle in the ovaries consists of an immature egg called an oocyte.
• Follicle cells are one cell layer thick.
• Granulosa cells are present when more than one layer is present.
• A primordial follicle consists of one layer of squamous like follicle cells surrounds the oocyte.
• A primary follicle has two or more layers of cuboidal granulosa cells enclose the oocyte.
• A secondary follicle has a fluid-filled space between granulosa cells that coalesces to form a central antrum.
• Follicles in which the antrum has become large and fully formed are considered Tertiary follicles.
• Ovulation is the ejection of the oocyte from the ripening follicle.
• The cervix is the narrowed neck which projects into the vagina inferiorly.
• Corpus luteum is a ruptured follicle after ovulation.
• Risk factors for breast cancer include early onset of menses or late menopause, no pregnancies or the first pregnancy late in life, previous history of breast cancer or family history, and hereditary factors including mutations to the genes BRCA1 and BRCA2.
• The menstrual cycle ends with the secretory phase, which occurs from days 15-28, when the endometrium prepares for implantation of the embryo.
• The mature follicle ruptures the ovarian wall during the luteal phase, which occurs from days 14-28 of the ovulation cycle.
• By the 8th week, all organ systems are recognizable.
• If pregnancy does not occur, the corpus luteum degenerates in 10 days, leaving a scar (corpus albicans).
• Pregnancy events occur from fertilization until the infant is born.
• Uterine tubes and oviducts receive the ovulated oocyte and provide a site for fertilization.
• The corpus luteum secretes progesterone and estrogen.
• During the follicular phase, the primordial follicle, directed by the ovary, grows to become a mature follicle.
• The pre-embryo is the conceptus from fertilization until it is 2 weeks old.