ANHB2216 Study Guide - Final Guide: Adipocyte, Malnutrition, Leptin
3 Jun 2018
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Course
Professor
The Life Cycle
Sexual Differentiation:
• Biological Sex
o Chromosomal sex → XX or XY
o Genetic sex → SRY gene
o Gonadal sex → ovary or testis
o Phenotypical sex → penis/scrotum or labia/clitoris
o Gender → roles, identity, presentation
• SRY Gene
o SRY protein → testis determining factor
o Upregulation of other genes → particularly Sox9
o Presence of the SRY gene results in the development of the testis
→ Sertoli and leydig cells, Spermatogonia
o Absence of SRY gene → forms ovary → granulosa and thecal cells,
oogonia
• Gonad Formation
o 2 tissue types
▪ Mesenchyme → matrix of gonad
▪ Primordial germ cells → gametes
o Primordial germ cells migrate from yolk sac to genital ridge ~
week 3
o Epithelial cells of genital ridge → somatic support cells
o Gonad is indifferent
o Week 7
▪ SRY gene expressed in somatic support cells → sertoli cells
▪ Sertoli cells form testis cords enclosing primordial germ
cells
▪ Testis cords → seminiferous tubules
▪ Leydig cells differentiate from mesenchyme cells ~ week 9-
10
▪ Sertoli cells produce AMH
▪ Leydig cells secrete testosterone
o No SRY gene
▪ Primordial germ cells differentiate into oogonia →
surrounded by somaic support cells
▪ Oogonia → primary oocyte and enter Meiosis I
▪ Somatic support cells → follicle (granulosa) cells
▪ Follicle cells surround oocyte to form primordial follicle
• Development of Internal and External genitalia
o Development of male internal and external genitalia dependent on
hormone activity
▪ Antimullarian hormone (AMH)
▪ Testosterone
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• Variations in sex
development
o Androgen
insensitivity syndrome
▪ Genetic mutation resulting in defective androgen receptors
▪ Phenotype at birth → female
▪ Infertility
o Androgen deficiency
▪ Mutation in genes that encode enzymes involved in
synthesis of testosterone or DHT
▪ Variable effects on internal and external genitalia
▪ 5�-reductase syndrome → male infants with female
external genitalia, masculinization at puberty
o Androgen excess
▪ Mutations in genes coding for enzymes that convert
progestin to corticosteroids
▪ Increase conversion of progestin to androgen
▪ Masculinization of female infants
▪ E.g. congenital adrenal hyperplasia
Sexual Maturation:
• Puberty → physiological, morphological and behavioral changes that
occur in a growing individual during the transition from a juvenile to a
fertile adult
• Adolescence → period of growing up between juvenile and adult
• Male puberty
o Phenotypic changes
▪ Genitalia increase in size (penis and scrotum)
▪ Pubic and axillary hair → due to adrenal androgens
▪ Adolescent growth spurt begins
▪ Lean body mass increase → anabolic effect of testosterone
▪ Testosterone effects on laryngeal muscle → deepens voice
▪ Accessory gland development → ejaculation
find more resources at oneclass.com
find more resources at oneclass.com
