These notes cover normal Postnatal Development during the puberty period which occurs mainly in the early teenage years. Triggers to puberty include neuroendocrine changes in hypothalamic expression of kisspeptin which is suggested in turn to change gonadotropin releasing hormone (GnRH) levels. (More? Kisspeptin | Gonadotropin Releasing Hormone | Endocrine Notes - Hypothalamus)
Male and female sexual differentiation giving the complete sexual phenotype involves two main phases.
Primary, the formation of an ovary or a testis from the bipotential gonad in the embryo.
Secondary is the development of the female and male phenotypes in response to hormones secreted by the ovaries and testes which occurs in the teen years during adolescence. This is initiated by the renewed expression of gonadotropin releasing hormone (GnRH) which is minimal in childhood.
Of general interest would be the timing differences between girls and boys when puberty commences (girls before boys). Early onset of puberty (precocious) occurs more frequently in girls than boys, in contrast late onset (delayed) occurs more frquently in boys than girls.
The UNSW Embryology section of notes covering endocrine development are therefore also relevant to your understanding teenage development. (More? Endocrine Notes Genital Notes)
Page Links: Introduction | Some Recent Findings | Puberty | Precocious Puberty | Delayed Puberty | Kisspeptin | Gonadotropin Releasing Hormone | Australian Information | American Information | Postnatal Neural Development | Reading | References | Glossary
Other Pages: Development of the Reproductive System | Integumentary Development - Mammary Glands | Integumentary Development - Hair | Endocrine Development - Hypothalamus | Week 1 - Oogenesis | Week 1 - Spermatogenesis |
Banerjee I, Trueman JA, Hall CM, Price DA, Patel L, Whatmore AJ, Hirschhorn JN, Read AP, Palmert MR, Clayton PE. Phenotypic variation in constitutional delay of growth and puberty: relationship to specific leptin and leptin receptor gene polymorphisms. Eur J Endocrinol. 2006 Jul;155(1):121-6.
"Constitutional delay of growth and puberty (CDGP) is a variant of normal pubertal timing and progress, often with dominant inheritance. It is likely that one or more genes will be associated with CDGP. Possible candidates are the leptin (L) and the leptin receptor (LR) genes, as the leptin axis links nutritional status to pubertal development. ...There was no association of specific L or LR polymorphisms with CDGP, but L short allele carriage influenced the phenotype within CDGP."
Seminara SB. Mechanisms of Disease: the first kiss-a crucial role for kisspeptin-1 and its receptor, G-protein-coupled receptor 54, in puberty and reproduction. Nat Clin Pract Endocrinol Metab. 2006 Jun;2(6):328-34.
"Ligands for G-protein-coupled receptor 54 (KiSS-1R), including metastin (derived from the parent compound, kisspeptin-1) and metastin's C-terminal peptide fragments, have been shown to be powerful stimulants for GnRH release in vivo via their stimulation of G-protein-coupled receptor 54."
Can occur over a broad range of time and differently for each sex: girls (age 7 to 13) boys (age 9 to 15).
The physical characteristics that can be generally measured are: genital stage, pubic hair, axillary hair, menarche, breast, voice change and facial hair.
The physiological process is initiated by the hypothalmus releasing gonadotropin releasing hormone (GnRH) which signals the pituitary to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH) which in turn signals throughout the body sexual development.
Links: Endocrinology - Puberty | Endocrinology - Endocrine changes in puberty | Endocrinology - Gonad | Clinical Methods - The Adolescent Patient | Clinical Methods - Staging Criteria for Secondary Sexual Development | NICHD - Puberty | UCSF - Male Development |
Premature development of the signs of puberty which can occur in both girls (before age 7 or 8) and in boys (before age 9).
Links: Endocrinology - Precocious sexual development | NICHD - Precocious Puberty | Nemours Foundation - Precocious Puberty | MedlinePlus - Obesity May Trigger Earlier Puberty for Girls | Time Magazine - Teens Before Their Time |
Determined in boys by a lack of increase in testicular volume by the age of 14 years. In girls, no breast development by the age of 13.5 years and a lack of menstruation by the age of 16 years. There can also be a "pubertal arrest" where there is no progress in puberty over 2 year period.
Links: Endocrinology - Delayed puberty | Endocrinology - Definitions and causes of delayed puberty | Nemours Foundation - Delayed Puberty
While the hypothalamic expression of gonadotropin releasing hormone (GnRH) is a known puberty trigger, it was not known what initiated the GnRH secretion. Recent research suggests that an earlier signal could come from increased neuronal and hypothalamic expression of a peptide family (kisspeptins) and their receptor (G protein-coupled receptor GPR54) in the hypothalamus. A single gene (Kiss1) encodes these 145 amino acid kisspeptins and it was originally identified as a human metastasis suppressor gene (suppresses melanomas and breast carcinomas without affecting tumorigenicity).
Two hypothalamic nuclei, the arcuate nucleus and anteroventral periventricular nucleus (AVPV), are thought to contain the kisspeptin secreting neurons.
The anteroventral periventricular nucleus differs in males and females (sexually dimorphic). The arcuate nucleus (and medial preoptic area, MPOA) is linked into the olfactory system, through the vomeronasal organ, perhaps in relation to the influence of pheromones on sexual behavior and neuroendocrine function (in mice).
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Why Kisspeptin? The original discovery of the peptide was made by scientists located in Hershey, PA, USA and named the gene "Kiss1" after the "Hershey chocolate kiss". |
References: Seminara SB. Mechanisms of Disease: the first kiss-a crucial role for kisspeptin-1 and its receptor, G-protein-coupled receptor 54, in puberty and reproduction. Nat Clin Pract Endocrinol Metab. 2006 Jun;2(6):328-34. | Dungan HM, Clifton DK, Steiner RA. Minireview: kisspeptin neurons as central processors in the regulation of gonadotropin-releasing hormone secretion. Endocrinology. 2006 Mar;147(3):1154-8.
Links: OMIM - KISS1 METASTASIS SUPPRESSOR | OMIM - G-protein-coupled receptor 54 |
Neurons in the hypothalamic arcuate nucleus (and other nuclei) synthesise this hormone along with gonadotrophin associated peptide (GAP), which are both released and transported by hypophyseal portal capillaries to the anterior pituitary and bound by a membrane receptor.
GnRH increases during early puberty, followed by an increased pituitary responsiveness, then increasing sex steroid levels and then increased nocternal Luteinizing hormone (LH) secretion.
Links: Endocrinology - GnRH and the control of gonadotrophin synthesis and secretion | Endocrinology - Synthesis of GnRH and its actions on pituitary gonadotrophs |
National Institute of Child Health and Human Development Puberty | Precocious Puberty
American Academy of Family Physicians Puberty: What to Expect When Your Child Goes through Puberty
Nemours Foundation Precocious Puberty | Delayed Puberty |
Most embryology textbooks (by definition) do not cover postnatal developmenty in any detail. The links below are to useful scientific external online resources.
The links below are to general public external text resources (this listing is for information purposes only and is not intended as an endorsement of a commercial product).
Links: Reviews | Articles | Online Textbooks | Search Textbooks | Search PubMed | Glossary
Muir A.. Precocious puberty. Pediatr Rev. 2006 Oct;27(10):373-81.
Palmert MR, Boepple PA. Variation in the timing of puberty: clinical spectrum and genetic investigation. J Clin Endocrinol Metab. 2001 Jun;86(6):2364-8.
Dungan HM, Clifton DK, Steiner RA. Minireview: kisspeptin neurons as central processors in the regulation of gonadotropin-releasing hormone secretion. Endocrinology. 2006 Mar;147(3):1154-8.
Articles
Banerjee I, Trueman JA, Hall CM, Price DA, Patel L, Whatmore AJ, Hirschhorn JN, Read AP, Palmert MR, Clayton PE. Phenotypic variation in constitutional delay of growth and puberty: relationship to specific leptin and leptin receptor gene polymorphisms. Eur J Endocrinol. 2006 Jul;155(1):121-6.
Search NCBI Bookshelf: puberty
Search PubMed
Search Aug 2006 "puberty" 23,525 reference articles of which 2,915 were reviews.
Search PubMed: term = puberty
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Who can understand a teenager? Well it turns out they are undergoing many physiological changes (growth and differentiation) beyond their own control, they don't even understand whats happening to them.
This section of notes covers early teenager, where hormonal changes trigger changes that lead to growth and reproductive maturation.
Note this current project focuses on prenatal development, so postnatal content is not as detailed.
Please email Dr Mark Hill if you wish to make a comment about this current project.