Reproductive unit female

Spatial separation and developmental divergence of male and female reproductive units in gymnosperms, and their relevance to the origin of the angiosperm flower... 

Yet the earliest fossil seed-plants from the Upper Devonian, such as Elkinsia polymorpha (Fig 2.6b Rothwell and Serbet, 1992) and Moresnetiazalesskyi (Fairon-Demaret and Scheckler, 1987), not only have unisexual reproductive units but may also be dioecious. If so, the onset of strong segregation of male and female reproductive organs coincides with, and hence maybe implicated in, the origin of the seed (Bateman and DiMichele, 1994). 

The development ofmale and female reproductive units directly on the large fronds traditionally attributed to the conceptual whole-plant MeduZZosa is confidently illustrated in most palaeobotany textbooks, but appeared developmentally improbable... 

Gamete A reproductive cell such as ovule or pollen. Female and male gametes unite to form a single cell called the zygote, which, through division, generates an embryo and ultimately a progeny individual. 

The number of individuals affected by reproductive disorders is difficult to assess, and few population-based data are available for either men or women. Noticeably absent are data on fecundity and fertility impairments affecting men and only limited information on male-mediated developmental outcomes exists. Population-based data for impaired female fertility are available for select endpoints from the National Surveys of Family Growth (NSFG), which are conducted periodically and most recently in 1995. Data from the NSFG show that 6.2 million women (10.2%) between the ages of 15 and 44 in the United States had impaired fertility in 1995 (Stephen 1996). This number was estimated to increase to 6.3 million women in 2000 (Stephen and Chondra 1998). Other reproductive disorders in females that impact fecundity include endometriosis and polycystic ovarian syndrome (PCOS). The prevalence of endometriosis in women of reproductive age is reported to be 10% (Houston 1984 Olive and Schwartz 1993), and no population-based prevalence data exist for PCOS. 

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