The effects of GnRH on the secretion of LH and FSH are not exactly parallel, and the variations are probably due to other modulating factors such as the serum concentrations of steroid hormones (substances secreted by the adrenal cortex, testes, and ovaries).
The noun OBSTACLE has 2 senses: 1. something immaterial that stands in the way and must be circumvented or surmounted. 2. an obstruction that stands in the way (and must be removed or surmounted or circumvented). Familiarity information: OBSTACLE used as a noun is rare.Dictionary entry details.. something immaterial that stands in the way and must be circumvented or surmounted. 2. an obstruction that stands in the way (and must be removed or surmounted or circumvented). Familiarity information: OBSTACLE used as a noun is rare.
1. countable noun. A hurdle is a problem, difficulty, or part of a process that may prevent you from achieving something. Two-thirds of candidates fail at this first hurdle and are packed off home. The weather will be the biggest hurdle so I have to be ready.