By Lennart Nilsson, 1965

Is Sex necessary for species to be created and maintained? We do not even in the least know the final cause of sexuality; Why new beings should be produced by the union of the two sexual elements, instead of by a process of parthenogenesis. ––––– Charles Darwin

So why Sex? Did it occur by accident? A dice played with universe by God?

Bryaninops-yongei-海鞭虾虎鱼

Sex is incredibly magic. The physiology related with sex is complex biological activity

Reproductive functions of the male and female Gonad Gland Testis Ovaries Germ cells Sperm Ovum Hormone-Producing cells Androgens (Testosterone) (Dihydrotestosterone) (Androstenedione) Estrogen Progesterone Pregnancy Lactation

Reproductive and Hormonal Functions of the Male I. Spermatogenesis II. Male Sex Hormones

Male Reproductive System Seminiferous tubule Male Reproductive System Interstitial cells (Leydig cells)

Spermatids Spermatozoa (23 chromosomes) Meiosis Mitosis

Factors Impacting Sperm Temperature: Cryptorchidism Disease: Inflammation/Tuberculosis X-Ray Smoking & Drinking

Functions of Testis Spermatogenesis --- Seminiferous tubule; Synthesis and Release of Androgens such as testosterone etc --- Interstitial Cells; Under influence of FSH and LH released from anterior pituitary gland respectively.

Functions of Testosterone To cause descent of the testes into scrotum; Effects on development of adult primary and secondary sexual characteristics (Distribution of body hair; Baldness; Voice; Acne; Protein formation and muscle etc…..)

Female Physiology Before Pregnancy and Female Hormones 1. Female Hormonal System? 2. Ovarian Follicle growth? 3. Secretion of estrogen and progesterone? 4. Interplay between Hypothalamic-Pituitary and ovarian Hormones? 5. Relations between Ovarian hormones and menstruation?

I. Female Hormone System Hypothalamus Gonadotropin-Releasing Hormone (GnRH) Gonadotropin Hormone: Follicle-Stimulating Hormone (FSH) Luteinizing Hormone (LH) Estrogen/Progesterone; Inhibin

Cyclical Secretion of FSH and LH Female sexual cycle in 28 days FSH and LH secreted by the anterior pituitary gland in cyclical rhythm regulate the cyclical ovarian changes and subsequent secretion of ovarian hormones. Importance: surge of LH and FSH?

II. Ovarian Follicle growth Histology of Ovarian Follicle Ovum Follicle cells Granulosa Thecal cells Proliferation and Secretion of Hormones are regulated by FSH and LH.

6-12 Lutein cells Granulosa & Theca cells Ovulation

III. Sex Hormone Secretion in Ovarian Cycle Luteal Phase Follicular Phase III. Sex Hormone Secretion in Ovarian Cycle Cell type Granulosa cells Lutein cells Hormone Estrogen Estrogen Progesterone (Inhibin) Estrogen Progesterone

Functions of the Ovarian Hormones Estrogen Effect on the Uterus and external female sex organs; Effect on the Fallopian Tubes and Breast; Effect on the Skeleton; Effect on Protein Deposition, fat deposition and Body metabolism; Effect on Hair Distribution and Skin; Effect on electrolyte Balance; Negative and Positive feedback effect on Anterior Pituitary Gland; Progesterone Effect on the Uterus, Fallopian tubes and Breast; Effect on the body temperature; Feedback effect on Anterior Pituitary Gland Before Ovulation After Ovulation

IV. Interplay between Hypothalamic-Pituitary and ovarian Hormones GnRH induces Anterior Pituitary Gland to Secret LH and FSH; LH and FSH regulate the follicle growth and subsequent estrogen and progesterone secretion; Negative feedback effects of estrogen and progesterone on LH and FSH secretion; Positive feedback effect of estrogen before ovulation -- LH surge

GnRH Estrogen Progesterone Estrogen Hypothalamus GnRH FSH LH Estrogen Progesterone Estrogen

Interplay between FSH/LH and Ovarian Hormones Hypothalamus ④ Estrogen (High Level) GnRH ① ⑧ Estrogen Progesterone (Inhibin) ⑨ Corpus Albicans ③ Estrogen (Low level) ② FSH、LH ⑥ Ovulation ⑤ LH↑ FSH↑ ⑦ Corpus Luteum LH Surge Interplay between FSH/LH and Ovarian Hormones

V. Relations between Ovarian hormones and menstruation Menstrual phase Proliferative phase Secretory phase