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1: J Clin Endocrinol Metab. 2007 Sep 11; [Epub ahead of print]

Developmental Changes in Human Fetal Testicular Cell Numbers and mRNA Levels
During the Second Trimester.

O'shaughnessy PJ, Baker PJ, Monteiro A, Cassie S, Bhattacharya S, Fowler PA.

Division of Cell Sciences, University of Glasgow Veterinary School, Bearsden Rd, 
Glasgow, G61 1QH, UK; Institute of Medical Sciences, Department of Obstetrics &
Gynaecology, University of Aberdeen, Aberdeen, AB25 2ZD, UK.

Context: Normal fetal testis development is essential for masculinisation and
subsequent adult fertility. The second trimester is a critical period of human
testicular development and masculinisation but there is a paucity of reliable
developmental data. Objective: To analyze second trimester human testicular
morphology and function. Design: An observational study of second trimester
testis development. Setting: The study was conducted at the Universities of
Glasgow and Aberdeen. Patients/Participants: Testes were collected from 57
morphologically normal fetuses of women undergoing elective termination of
normally progressing pregnancies (11-19 weeks of gestation). Main outcome
measure(s): Testicular morphology, cell numbers and quantitative expression of 22
key testicular genes were determined. Results: Sertoli cell and germ cell number 
increased exponentially throughout the second trimester. Leydig cell number
initially increased exponentially, but slowed towards 19 weeks. Transcripts
encoding Sertoli (KITL, FGF9, SOX9, FSHR, WT1) and germ (CKIT, TFAP2C)
cell-specific products increased per testis through the second trimester but
expression per cell was static apart from TFAP2C which declined. Leydig cell
transcripts (HSD17B3, CYP11A1, PTC1, CYP17, LHR, INSL3) also remained static per 
cell. Testicular expression of "adrenal" transcripts MC2R, CYP11B1, CYP21 was
detectable, but unchanged. Expression of other transcripts known or postulated to
be involved in testicular development (GATA4, GATA6, CXORF6, WNT2B, WNT4, WNT5A) 
increased significantly per testis during the second trimester. Conclusions: The 
second trimester is essential for establishment of Sertoli and germ cell numbers.
Sertoli and Leydig cells are active throughout the period but there is no
evidence of changing transcript levels.

PMID: 17848411 [PubMed - as supplied by publisher]

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