uterus is a very important reproductive organ for implantation and holding embryos till labor. Many drugs and medicinal plants affect the uterus, some researchers reported that Salvadora persica (Miswak) is a phytoestrogen plant as it contains flavonoids and can be used as a contraceptive drug; however, no available investigations explain the histomorphological structure of the uterus after Miswak extract administration. Twelve female albino rats (165.3 ± 3.269 g) were divided equally into two groups.  In the control group, the animals received normal saline daily for 4 weeks. While in the Miswak treated group, the animals received 900 mg/kg of body weight of the Miswak aqueous extract daily for the same period. Grossly, at the end of the experiment, our results revealed that the uteri in the Miswak-treated group had characteristics of low active organs; they were pale with low weight and high thickness. In contrast to the treated group, the uteri of the control group had the signs of active organs; they were more vascular, relatively thin and edematous. Microscopically, in the control group, the uterine lumen was wide and the mucosa was folded and covered by secretory columnar epithelium. The uterine glands were more active, and the myometrium was thick. Whereas, in the Miswak-treated group, the lumen was slit-like, the uterine glands were less active, and the uterine wall had thick lamina propria and thin myometrium. In conclusion, the oral administration of Miswak extract reduces the uterus activity. It showed a state of anestrous with a narrow slit-like lumen and a decrease in glandular activit

Isoforms of the smooth muscle myosin phosphatase targeting subunit 1 (MYPT1) are generated by cassette-type alternative splicing of exons. Tissue-specific expression of these isoforms is thought to determine smooth muscle-relaxant properties and unique responses to signaling pathways. We used mini-gene deletion/mutation constructs to identify cis regulators of splicing of the chicken MYPT1 central alternative exon. Comparisons of alternative exon splicing were made between smooth muscle cells of the fast-phasic contractile phenotype (gizzard), in which the central alternative exon is skipped, and slow tonic contractile phenotype (aorta), in which the alternative exon is included. We demonstrate that splicing of the alternative exon requires a cis-enhancer complex in the vicinity of the alternative exon 5'-splice site. This complex consists of two UCUU motifs in an intronic U-rich sequence (putative PTB (polypyrimidine tract binding) or T cell inhibitor of apoptosis-1 binding sites), an intronic 67-nucleotide enhancer that has similarities with the cardiac Troponin T MSE3 enhancer, and a potentially novel exonic splicing enhancer. The exonic enhancer contains the palindromic sequence UCCUACAUCCU present in many other transcripts where alternative splicing of exons occurs, suggesting that it may be more broadly active. The exonic enhancer is adjacent to a potentially novel exonic silencer element that contains a 13-nucleotide imperfect palindromic sequence. This silencer, in conjunction with a distal intronic silencer, is proposed to mediate the silencing of splicing of the MYPT1 central alternative exon in the fast phasic smooth muscle phenotype