reproductive system

• Reproduction is the survival of species, producing offspring/ new individuals, and generating genetic variations.
• The penis has a cuff around the glans which is removed if circumcision is performed.
• The testes are small, paired oval organs that house the scrotum and produce sperm and androgens.
• The male external genitalia consists of the scrotum, penis, and testes.
• The skin of the penis is loose and covered by the foreskin.
• The urethra has three erectile bodies: the corpus spongiosum, the pair of corpora cavernosa, and the urethra itself.
• The penis has three parts: the root which is attached, the free shaft or body, and the enlarged tip called the glans penis.
• The scrotal wall consists of skin, fascia, dartos muscle, external and internal spermatic fascia, Cremaster muscle, Tunica vaginalis, and has a scrotal septum which internally divides the scrotum into two sacs: the subcutaneous layer and the dartos muscle.
• The penis also has the urethra, also known as the spongy or penile urethra.
• Supporting structures of the male external genitalia include the scrotum which supports the testes and maintains temperature, and the penis which is used for sexual intercourse and delivers sperm.
• The scrotum is an outpouching skin that contains the testes and is a skin-covered sac.
• Normal sperm production requires a temperature of 2 - 3 ˚C below core body temperature.
• Ejaculation is caused by sympathetic nerves which contract the smooth muscle of the ducts and penis.
• The male and female must “work” together to produce gametes through sexual maturation and activities.
• After 5 weeks, the prosencephalon will develop into secondary brain vesicles: telecephalon, diencephalon, and metencephalon.
• Neurulation is the developmental process of neural plate, neural folds and neural tube, where the notochord induces ectodermal cells to form a neural plate, the lateral edges of the neural plate become more elevated and form neural fold, and the depressed midregion is called neural groove.
• The chorion surrounds the embryo/fetus and becomes the placenta, protecting the embryo from immune responses by secreting proteins that block antibody production by the mother and promoting the production of T-lymphocytes.
• Placentation is the process of forming the placenta, which functions as the site of exchange of nutrients and wastes between mother and fetus, hormone production (pregnancy), and a protective barrier (microbe, viruses).
• Gastrulation is the developmental process that involves the reorganization of cells from the epiblast, where invagination occurs and epiblast cells move inward.
• Development of the chorion begins from the fused extraembryonic mesoderm, forming a larger cavity.
• The umbilical cord is the connection between the placenta and embryo.
• After 4 weeks, the neural tube will develop into primary brain vesicles: forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon).
• The chorion produces hCG and pregnancy hormones.
• Fusion of neural folds and neural plate changes into a neural tube.
• Both the trophoblast from the embryo and the endometrial tissue from the mother contribute to the formation of the placenta, which is not called placenta until the 4th month.
• Sexual reproduction involves the separation of sexes, specialized reproductive structures, hormonal control and mechanisms, and forms of behavior.
• Hermaphroditism is the condition where there is no separation of sex organs, and it can be protogynous or protandrous.
• Modified sweat glands are found in both sexes but function (normally) only in lactating female.
• The female reproductive cycle encompasses the ovarian and uterine cycle, hormonal changes that regulate them, and related changes in breast and cervix.
• Follicle - stimulating hormone (FSH) initiates follicular growth and stimulates ovarian follicles to secrete estrogens.
• Muscles underneath the nipple include pectoralis major and minor, parts of serratus anterior and external oblique.
• Mammary glands consist of 15 - 25 lobes, each a distinct compound alveolar gland opening at the nipple, separated by adipose and suspensory ligaments, with smaller lobules composed of tiny alveoli or acini.
• Relaxin is produced by corpus luteum and relaxes uterus by inhibiting contraction of myometrium.
• Estrogens are secreted by ovarian follicles and promote development and maintenance of female reproductive structures and secondary sex characteristics.
• Inhibin is secreted by granulosa cells of growing follicles and by corpus luteum and inhibits secretion of FSH and LH.
• The nipple is surrounded by a pigmented ring of skin known as the areola.
• Luteinizing hormone (LH) stimulates further development of ovarian follicles and stimulates thecal cells of developing follicle to produce androgens to be converted into estrogens.
• The phases of female reproductive cycle range from 24 - 35 days.
• The uterine (menstrual) cycle is a concurrent series of changes in uterine endometrium preparing it for arrival of fertilized ovum.
• Gonadotrophin - releasing hormone (GnRH) is secreted by hypothalamus, controls ovarian and uterine cycle and stimulates releases of FSH and LH from anterior pituitary.