Behind the mesh wire, behind the brown bars in the Montgomery County Detention Center, there are prisoners and there are beds. Skinny cots. Makeshift bunks. Thin blue mattresses on the concrete floor.

In a jail built to house 30 women and 242 men, there are beds everywhere. Four hundred and twenty of them most nights.

Seven mattresses on the floor are squeezed between 10 bunk beds in a 15-by-25-foot room closed six years ago, but reopened last year when there was nowhere else to place the overflow of prisoners. Cots are crammed together in recreation rooms designed only for day use; flimsy mattresses on emergency loan from Prince George's County are laid in an upstairs hallway.

To say the Montgomery County jail is chronically overcrowded is to state the obvious or the frequently heard in a state where nearly every jail is packed past capacity. The state is under three court orders to relieve overcrowding. But in Montgomery County, as elsewhere in the nation, the grievance once sounded solely by male prisoners is now being voiced loudly and stridently in the women's wing.

Two years ago on an average night, local officials say, there might have been two or three women housed in the Rockville jail. Some nights now that number shoots up to 50.

Although that figure is slight compared to the male inmate population, the quintupling, nonetheless, jail officials say, has turned the women's section of the chalk-white Rockville facility into an overstuffed storehouse of bodies and beds.

In particular, jail officials say, they are watching nervously as the special problems of caring for female inmates are exacerbated as space shrinks. Tension is up among prisoners, understaffing has caused a drop in services for inmates and morale is low among guards.

Says detention center Warden Samuel F. Saxton, "Severe overcrowding lessens our ability to deal with everything" throughout the jail, but in the women's wing, "we don't have the flexibility that we have in the male wing."

The quantum leap in women inmates was not anticipated when the jail was built in 1961 or when it was expanded in 1978, Saxton explains. As a consequence, the side-wing women's section of the jail juts out like an afterthought and has only two small sections divided by a hallway.

In the male wing, if a problem erupts among inmates, the prisoners can be moved to a number of different sections of the jail: one of several 24-man pods, isolation cells or the dormitory. With the women, if there is a problem, guards can only place them on one side of the hall or the other.

In Prince George's County, where county officials agreed last week to build a new detention center by 1985, the number of women inmates has tripled from about 10 a night four years ago to about 30 a night now. In the entire jail, 550 prisoners, men and women, are stuffed into a space designed to house 143, according to county officials.

In the Maryland Correctional Institute for Women in Jessup, the state's only institution for women, 317 inmates squeeze into space intended for 184. Some are housed in the basement.

In an effort to relieve some of this warehousing of bodies, Montgomery Corrections Director Gary Blake has asked for $7 million to expand the women's wing of the county's prerelease center, which is operating at more than a third of its planned capacity, and the detention center.

County Executive Charles W. Gilchrist included half of the request--$3.5 million--in Montgomery's 1983 capital improvements budget. And this week, the General Assembly's House Appropriations Committee heard requests that the other $3.5 million be included in Gov. Harry Hughes' $35 million request for prison construction next year.

If it's approved, corrections officials expect to begin building in July 1983. Half of the money would be used to expand the women's sections of both institutions, with 20 beds planned for the women's wing of the prerelease center and 52 beds for the detention center. Seventy-two beds would be added to the men's wing in the detention center.

Corrections officials give several reasons for the sharp rise in the number of female inmates: an overall get-tough attitude sweeping through the nation's courtrooms, less leniency by judges in the sentencing of women and the women's movement.

"When women's liberation came into being it did not just affect the free and educated women," says Saxton. "It blew across the entire spectrum and one of those [areas] was crime. We have begun to see women involved in types of crimes where we had never seen them before."

Although women form only 4 percent of the prison population nationwide, the number of women in jails has almost doubled in the last seven years. In 1974 there were 7,400 women in state and federal prisons. In 1981 that number rose to 15,000, according to Justice Department statistics.

Women's jail Warden Rosa Lynn says she has witnessed, in addition to an increase in numbers, a change in the types of crimes women are committing. Previously, she said, most women were accused of shoplifting.

"Not too long ago, the women here were involved in a lot more passive crime. But that's not true anymore," said Lynn. "The women are just as aggressive as the males. We see armed robbers, murderers, everything."

On a recent afternoon in the women's section, the inmates included a woman accused of murdering a man and severely slashing a woman, an armed robber and two women charged with assault. The majority of the women, however, were charged with theft or drug-related crimes, according to statistics released by the county's corrections department.

Nationally, the number of women involved in violent crimes also has risen. Ten years ago, 90 percent of all violent crimes were committed by males and 10 percent by females. Last year, 22 percent of all violent crimes were attributed to females and 78 percent to males, according to Department of Justice statistics.

Still, says Hardy Rauch, a spokesperson with the American Correctional Association and a former warden at the federal penitentiary in Lexington, Ky., the majority of crimes by women are "certainly of the nonviolent nature. They are usually drug-related or white-collar crimes."

Although local officials are waiting for the nod to go ahead with the expansion of the prison facilities, correction officials say it may be only a matter of time and inmate numbers before something rocks the local jail into violence. Last month, a day room was set on fire; earlier, two women had to be separated by guards after breaking into a fist fight when one accused the other of staying on the phone too long.

"It's these little things that throw everyone out of control," says guard Rentha Butler. "It gets tense. Everybody just wants their space and there just isn't space anymore."