Ovule number

Lacker, H.M. 1981. The regulation of ovulation number in mammals An interaction law which controls follicle maturation. Biophys. J. 35 433-54. 

Fig 3.12 Selected floral characters mapped on the hackhone tree of Doyle and Endress (2010) with fossil Cohongarootonia hispida (PP53716) included. (A) Carpel number. (B) Ovule number. 

The pathophysiologic changes that occur during the perimenopausal and menopausal periods are caused by the decrease and eventual loss of ovarian follicular activity. As women age, the number of ovarian follicles decreases, and the remaining follicles require higher levels of FSH for maturation and ovulation. During perimenopause, FSH concentrations... 

Ovulation is considered a hostile event to the ovarian epithelium, making it more susceptible to damage and cancer. Interventions or conditions that limit the number of ovulations in a woman s reproductive history will have a protective effect. For instance, multiparity would decrease the number of ovulations. 

Another problem is the direction of pollen tube growth, which should be considered as tropism, related to attraction by the fertile ovules. Many observations of pollen tubes in the fluorescence microscope supported this suggestion—pollen tubes pass by the sterile ovules and grow in the direction of the fertile ones. The number of ovules penetrated by a pollen tube is correlated with the number of developing seeds, which supports the hypothesis about interaction (attraction) between the ovule and pollen tube (1,2,5). 

Abstract A relatively small number of mammalian pheromones has been identified, in contrast to a plethora of known insect pheromones, but two remarkable Asian elephant/insect pheromonal linkages have been elucidated, namely, (Z)-7-dodecen-1-yl acetate and frontalin. In addition, behavioral bioassays have demonstrated the presence of a chemical signal in the urine of female African elephants around the time of ovulation. Our search for possible ovulatory pheromones in the headspace over female African elephant urine has revealed for the first time the presence of a number of known insect pheromones. This search has been facilitated by the use of a powerful new analytical technique, automated solid phase dynamic extraction (SPDE)/GC-MS, as well as by novel macros for enhanced and rapid comparison of multiple mass spectral data files from Agilent ChemStation . This chapter will focus on our methodologies and results, as well as on a comparison of SPDE and the more established techniques of solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE). 

Intermediate-duration studies with treated females show that exposure to chlordecone may result in persistent vaginal estrus, decreased ovulation, and reproductive failure. Persistent vaginal estrus was observed in female mice at doses as low as 2 mg/kg/day for 3-6 weeks (Huber 1965 Swartz and Mall 1989 Swartz et al. 1988). Increased atresia of follicles (Swartz and Mall 1989), decreased ovulation (Swartz et al. 1988), and small and medium-sized follicles (Swartz and Mall 1989) have been observed after 4 weeks of exposure to 8 mg/kg/day of chlordecone. Similarly, decreased corpora lutea have been observed following administration of 3.9 mg/kg/day for 130 days (Huber 1965). Decreased numbers of litters or complete reproductive failure have been observed after exposure of female rats to 1.62-1.71 mg/kg/day for 4.5 months or female mice to 5.2 mg/kg/day for 160 days (Huber 1965). 

Figure 19.6 A 28-day menstrual cycle. The approximate number of days for menstruation, ovulation and the follicular and luteal phases are shown.

The first cell division of meiosis occurs in the primary oocyte but the process is arrested during prophase and remains so until puberty. Just before ovulation, meiosis, which has been arrested since before birth, resumes. The first division halves the number of chromosomes to produce the haploid secondary oocyte. The process is the same as that in spermatozoa (Chapter 20 see Figure 20.29 ) except that the two resulting haploid daughter cells are unequal in size. One is the large functional secondary oocyte whereas the other is much smaller and is known as the first polar body. The second meiotic division is arrested at metaphase. It is completed only at fertilisation. Once again, the division is unequal. One cell is large, the secondary oocyte. The other is small, a second polar body, which is discarded. 

An extract of secretion from the sebaceous glands on head and neck of sexually active feral billygoats increases the number of does ovulating. The extract was placed on cotton wool and worn in facemasks. 4-Ethyloctanoic acid and 4-methyloctanoic acid, responsible for the goaty odor, were not active but both the free fatty acid and lipid-free non-acid fractions were. The 4-ethyl branched fatty acids are present in the active fraction (Birch etal., 1989). 

Reproductive studies showed that 14 pairs of mice that received 40 ppm chlordecone in the diet for 2 months before mating and during the test produced no litters, whereas 14 control pairs produced 14 first litters and 14 second litters. Further studies in mice found that infertility in chlordecone-exposed females was due to an absence or reduction in the number of ovulated oocytes. Prenatal exposure of rats has also been shown to persistently alter neurobehaviors in adults. ... 

Female bw gain pre-mating decrease MMing-. usually unaffected Fertility, fecundity (number of ovulated oocytes, corpora lutea, litter size) slightly reduced (often encountered in high-dose group animals)... 

In females, the target organs are the ovaries where it increases the number and size (maturation, development and ripening) of Graafian follicles and prepare them for ovulation. During its development, the ovarian follicles secrete its own hormone estrogen. In males, it stimulates spermatogenesis. Under the influence of this hormone, seminiferous tubules produce spermatozoa. 

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